Curved draft tongue for mower conditioners

ABSTRACT

A curved implement tongue improves the turning characteristics of the implement, such as a mower-conditioner. The tongue is bent in the horizontal plane and incorporates a generally vertical box section at the end of the tongue. The tongue supports a driveline transmitting rotational power from a prime mover to the operative components of the mower-conditioner.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. patent application Ser. No.08/752,123, filed Nov. 20, 1996, now abandoned, claiming domesticpriority on U.S. Provisional patent application Ser. No. 60/007,507,filed Nov. 22, 1995, and U.S. Provisional patent application Ser. No.60/009,237, filed Dec. 26, 1995.

BACKGROUND OF THE INVENTION

Pull-type harvesting implements utilize a draft tongue to connect theimplement to the hitch of a tractor. The tongue is pivotally supportedfrom the frame of the implement to permit the tongue to pivotally moverelative thereto so that the implement can move from a transportposition directly behind the tractor to an operative position behind thetractor, but offset to the side thereof.

The draft tongue also supports a drive line connectable to thepower-takeoff shaft of the tractor to deliver rotational power to theoperative components of the harvesting implement, such as the cuttingmechanism and other crop harvesting apparatus supported from the frameof the implement. The drive line typically incorporates severaluniversal joints to permit bends in the drive line to accommodate thepivotal movement of the tongue as the implement is moved between thetransport and operative positions.

Typically, the frame of the harvesting implement will be made mobilethrough a pair of transverse wheels. When the harvesting implement isoperated in the operative position and offset outboard of the tractor,it will often be necessary to change the direction of travel of theimplement, which is accomplished through the turning of the tractor. Ifan imaginary line is extended from the rear axle of the tractor to aline corresponding to the axle of the implement interconnecting thetransverse wheels, a point of intersection is obtained. The closer thepoint of intersection is to one of the implement wheels, the tighter theimplement will be turned.

Several tongue and hitch designs have been provided to provide tighterturning characteristics. One such design is commonly referred to as theequal angle hitch mechanism in which the pivot point between the drafttongue and the tractor is located midway between the first two universaljoints of the drive line so that any turns result in equal turning ordeflection angles in the first two universal joints.

Another design is commonly referred to as the swivel hitch design asrepresented in U.S. Pat. No. 5,099,937. In this design, the turningmovement is pivoted through a gearbox to eliminate the angulardeflections in the drive line universal joints. While this swivel hitchdesign allowed a greater turning movement of the tractor relative to thedraft tongue, and as a result moved the point of intersection of theline of the tractor axle with the line of the implement axle closer tothe left implement wheel, further improvement is still available.

John Deere Company developed a bent implement tongue design to improvethe turning characteristics of the implement, as is represented in U.S.Pat. No. 5,018,345. While this draft tongue design improves theimplement turns, the tongue requires a bumper on the side of the tongueto prevent damage due to interference with the tractor tire.

It would be desirable to provide an implement tongue design that wouldbe aesthetically pleasing, while improving implement turningcharacteristics.

Disc cutterbars have been utilized in agricultural harvesting implementsfor many years. Each disc cutterbar includes a plurality of transverselyspaced disc cutters driven for rotation about a generally vertical axis.Each disc cutter has two or three knives pivotally mounted on theperiphery thereof to sever standing crop from the ground through animpact action. For background information on the structure and operationof disc cutterbars, reference is made to U.S. Pat. No. 4,815,262, issuedto E. E. Koch and F. F. Voler, the descriptive portions thereof beingincorporated herein by reference.

The construction of disc cutterbars has evolved over the years to theconfiguration of having a modular construction with cutter modules andspacer modules, such as shown in U.S. Pat. No. 4,840,019, issued to L.J. Pingry, the descriptive portions of which are incorporated herein byreference. In some instances, the cutter modules and the spacer moduleswere integrally formed into one unit such as shown and described in U.S.Pat. No. 4,947,629, issued to R. Ermacora and H. Neuerburg.

It has been found that the specific use of the disc cutterbar apparatus,e.g. whether used as part of a disc mower, such as shown and depicted inU.S. Pat. No. 4,955,187, issued to C. van der Lely, which is typicallysupported at one end, or as part of a disc mower-conditioner whichusually provides support to the cutterbar at both opposing ends thereof,carries with that use a different set of design parameters than othermachines in which the cutterbar is utilized.

On a disc mower-conditioner drive shaft, the secondary power-takeoffdrive shaft is typically supported in a cantilevered manner off of thefront of the splined input shaft of the main bevel gearbox. Included onthe secondary drive shaft is a constant velocity universal jointassembly and a slip clutch, both of which are quite heavy. Thepower-takeoff shaft is retained on the input shaft by a split clamp hubdesign.

As the power-takeoff shaft turns at high speeds, the centrifugal forcesresulting from the unbalanced shaft/universal joint/clutch assembly arecarried by the input shaft spline teeth and clamp joint. The secondarycouple from the universal joints in the constant velocity joint are alsoimposed on the input shaft. The spline fit with the clutch hub is looseintentionally so that the assembly can be installed over the splinedshaft.

This looseness of the external and internal spline teeth permits theassembly to be positioned off-center to the shaft. The centrifugalforces from the off-center mass and the forces of the secondary couplecause the assembly to whirl about the shaft centerline. The motion ofthe inner and outer splined parts wears the spline teeth causing morespline tooth clearance and increased relative motion, eccentricity andforce as the machine is used.

The clamped split hub retains the splined hub to the splined shaftadjacent to the clamp, but not away from the clamp area. The reactionfrom the secondary couple is carried partly by the clamped hub portionwhich causes relative motion between the clamped mating surfaces in theclamp area. The spline teeth in the clamp area are, therefore, subjectedto the same wear problem.

The centrifugal forces from the eccentric constant velocity universaljoint/clutch assembly and from the secondary universal joint couple aresupported by the bevel gearbox input shaft. The alternating forces cancause the input shaft to fail in fatigue resulting in the shaft to haveto be made larger and/or be heat treated to withstand the forces. Thesupport of the bevel gearbox also carries the vibrating forces and is,therefore, prone to failure as well.

Several alternative design solutions have been proposed to resolve thefixation problem of the clutch hub on the shaft, including an axiallyplaced bolt that screws into the end of the input shaft to clamp theclutch hub against the end of the input shaft and rigidly fix the clutchfor better support thereof, but did not adequately resolve the problemas these designs became loose over time. A further disadvantage wasrecognized in that the alternative designs did not include an alignmentfeature to position the drive shaft/constant velocity joint/clutchassembly concentrically about the shaft centerline.

SUMMARY OF THE INVENTION

It is an object of this invention to overcome the disadvantages of theprior art by providing a curved implement tongue for amower-conditioner.

It is a feature of this invention that the implement tongue extendingforwardly of the frame of the mower-conditioner for attachment to aprime mover, such as a tractor, is bent in a horizontal plane at theforward end of the tongue.

It is an advantage of this invention that the curved implement tongueimproves turning characteristics for the mower-conditioner.

It is another feature of this invention that the driveline supported bythe curved implement tongue incorporates a pair of constant velocityjoints to accommodate any misalignment of the driveline during sharpturns of the implement.

It is another advantage of this invention that the implement tongue doesnot require an interference structure that is engageable with thetractor tire to restrict the severity of the implement turn to preventunacceptable joint angles in the implement driveline.

It is still another advantage of this invention that the joint angles inthe driveline are not excessive whenever the implement is turned sosharply that the tractor tire can rub against the tongue structure.

It is still another feature of this invention that the forward end ofthe tongue incorporates a generally vertical box section to support agearbox operable to elevate the driveline.

It is another object of this invention to provide a curved implementtongue for a mower-conditioner which is durable in construction,inexpensive of manufacture, carefree of maintenance, facile inassemblage, and simple and effective in use.

It is still another object of this invention to overcome thedisadvantages of the prior art by providing a conical shaft support forthe driveline of a mower-conditioner.

It is yet another feature of this invention that the clutch assemblyincorporates a conical hub bore to receive the mating conical distal endof the input shaft for improved support thereof.

It is yet another advantage of this invention that the contact betweenthe conical shaft end and the conical hub bore centers the assembly tominimize any eccentricity of the rotating mass.

It is a further feature of this invention that the input shaft end isformed as a truncated cone to provide a gap between the end of the shaftand the bottom of the hub bore to assure proper seating of the shaftinto the bore.

It is a further advantage of this invention that the elimination of therelative motion between the clutch hub and the end of the shaft lessensthe chance of failure of the driveline components due to eccentricforces incurred therein.

It is yet another object of this invention to provide a shaft supportwithin a clutch assembly for a mower-conditioner which is durable inconstruction, inexpensive of manufacture, carefree of maintenance,facile in assemblage, and simple and effective in use.

These and other objects, features and advantages are accomplishedaccording to the instant invention by providing a curved implementtongue to improve the turning characteristics of the implement. Thetongue is bent in the horizontal plane and incorporates a generallyvertical box section at the end of the tongue. The tongue supports adriveline transmitting rotational power from a prime mover to theoperative components of the mower-conditioner. The drivelineincorporates a clutch assembly mounted on the input shaft of a bevelgearbox. The forward end of the input shaft is formed with a conicalsurface that mates with a corresponding conical hub bore formed withinthe clutch assembly. The end of the input shaft is formed as a truncatedcone to provide a gap between the end of the shaft and the bottom of thebore and assure a proper seating of the two members.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages of this invention will be apparent upon consideration ofthe following detailed disclosure of the invention, especially whentaken in conjunction with the accompanying drawings wherein:

FIG. 1 is a schematic top plan view of a draft tongue for a harvestingimplement commonly referred to as a disc mower-conditioner, the tonguebeing pivotally hitched to a tractor and being shown in three pivotedpositions, operative, transport and shipping, the tractor tires beingshown in the operative and transport positions and while turning leftand right in the operative position;

FIG. 2 is a bottom plan view of the draft tongue;

FIG. 3 is a partial elevational view of the forward portion of the drafttongue corresponding to lines 3--3 of FIG. 2;

FIG. 4 is a partial exploded perspective view of a discmower-conditioner trail frame assembly depicting the left end of theheader assembly suspended therefrom;

FIG. 5 is an enlarged elevational view of the constant velocityuniversal joint/slip clutch assembly; and

FIG. 6 is an enlarged partial cross-sectional view of the slip clutchand input shaft depicted in FIG. 5.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The structure of the disc mower-conditioner can best be found inApplicant's co-pending U.S. patent application Ser. No. 08/670,060,entitled "Disc Mower-Conditioner", the descriptive portions of which areincorporated herein by reference. Furthermore, the structure of themodular disc cutterbar forming an integral part of the header assemblyof the disc mower-conditioner is best described in Applicant's copendingU.S. patent application Ser. No. 08/673,604, entitled "Disc Cutterbarfor Agricultural Implements", the descriptive portions of which areincorporated herein by reference.

Referring to all of the drawings, it can be seen that the implement 10,shown in the form of a disc mower-conditioner, is provided with a frame12 made mobile through support of a left ground engaging wheel 13 and aright ground engaging wheel 14. A transverse disc cutterbar 15 isforwardly supported from the frame 12 and comprises a plurality oftransversely spaced rotatable disc members 17 that sever standing cropthrough an impact action.

The frame 12 is pivotally connected via a pivot joint 21 at the leftside thereof to a draft tongue 20 that extends forwardly therefrom toconnection with the tractor T. The tongue 20 is formed preferably from atubular beam of a cross sectional configuration sufficient to withstandthe draft forces, such as a six inch square tubular beam. The rearwardportion 23 of the tongue 20 extends linearly from the pivot 21 to acurved portion 25 near the distal hitch end 27 of the tongue 20. Sincethe implement 10 is customarily operated to the right of the tractor T,the curved portion 25 of the tongue 20 displaces the distal hitch end 27horizontally to the right of a line extending forwardly from therearward linear portion 23.

The forward or distal hitch end 27 is constructed of a generallyvertically oriented box section 26 to support a fixed gear box 35 thatelevates the drive line 30 from the elevation of the tractorpower-takeoff shaft 32 to the-elevation desired to extend the drive line30 rearwardly to the implement while being supported from the tongue 20.The drive line 30 preferably incorporates a first constant velocityjoint 33 to accommodate any misalignment between the tractorpower-takeoff shaft 32 and the drive line 30. Preferably, the firstconstant velocity joint 33 is operable through a displacement angle of80 degrees as operation may be desirable while the tractor isundertaking either a left or right turn, as demonstrated in FIG. 1, withthe tongue in the operative position A.

The drive line 30 preferably further incorporates a second constantvelocity joint 34 forwardly of the gear box 35 to accommodate bends inthe drive line 30 during left and right turns. A third constant velocityjoint 36 is positioned in the drive line 30 immediately rearwardly ofthe gear box 35 to accommodate angular displacement of up to 50 degreesof the drive line 30 when the tongue is moved between the operativeposition A and the transport position B. The shipping position C of thetongue 20 is used only for shipping the implement by carrier. A fourthconstant velocity joint 37 is positioned forwardly of the fixed support39 of the drive line 30 from the frame 12 to accommodate also themovement of the tongue 20 between the operative position A and thetransport position B.

As can be seen in FIG. 1, the right hand turn of the tractor T placesthe adjacent rear tire 41 of the tractor T at the curved portion 25 ofthe tongue 20, which permits a greater turning angle for the tractor Tthan if the tongue 20 were to extend linearly from the pivot 21 to thedistal hitch end 27. As a result, an imaginary line 45 corresponding toan extension of the rear tractor axle 42 intersects the implement axlevery close to the left implement wheel 13. The result is that the hardright turns of the tractor T will substantially result in the implement10 being turned about the left wheel 13, thereby creating sharpimplement turns needed to make efficiently square corners at the end ofa field of crop being harvested.

The resolution of the fixation problem outlined above with respect tothe eccentric and centrifugal driveline forces causing excessive wear inthe splined connection of the driveline is provided by shaping the endof the input shaft 5 with a conical end 9 that seats into acorresponding conical shaped hole in the end of the clutch hub bore 6A.A gap 9A is provided between the end of the shaft 5 and the hub bore 6Ato ensure that the conical surfaces seat fully. The angle of the shaftend 9 and the hub bore 6A is nominally identical so that they seatagainst each other when a screw SA is utilized to push the hub 4 ontothe shaft 5.

The power-takeoff shaft assembly 1 having a constant velocity universaljoint 2 and a slip clutch 3 are supported by 30 the input shaft 5 of abevel gearbox 4. The clutch hub 6 is split and is clamped onto the shaft5 with a bolt 8 adjacent the bevel gearbox 4. The forward end 9 of theinput shaft 5 is machined to form a conical shape, as best seen in FIG.6. The bottom of the clutch hub bore 6A is also machined to form aconical shape corresponding to the end 9 of the input shaft 5, such thatwhen the hub 6 is pushed onto the shaft 5 by the clamp bolt 5A, the twoconical surfaces come in contact to form a secondary support of theclutch assembly. A gap 9A is located between the shaft end 9 and theclutch hub bore 6A to ensure that the conical surfaces of the end 9 andthe bottom of the hub bore 6A will seat fully.

The contact of the angled surface of the two parts 9 and 6A supports theconstant velocity universal joint and the clutch assembly centrifugalforces as well as the universal joint secondary couple forces. Inaddition, the conical surfaces center the universal joint/clutchassembly on the shaft centerline to reduce the eccentricity of thedriveline design and, therefore, reduce the centrifugal forces generatedby an off-center rotating mass.

The contact between the input shaft and the hub bore conical surfaces ofthis driveline design centers the assembly of the power-takeoffshaft/constant velocity joint/clutch to provide the advantage ofminimizing the eccentricity of the rotating mass relative to the shaftand, as a result, minimizing the centrifugal forces imposed on theshaft. This driveline design also has the advantage of eliminating therelative movement between the shaft external and internal spline teeth,which prevents wear therebetween and the resultant increased looseness.Furthermore, the more precisely positioned universal joint/clutchassembly and the elimination of the relative motion between the clutchhub and the input shaft greatly reduces the alternating forces on theinput shaft and bevel gearbox support, thereby lessening the chance thatthese components will fail due to fatigue.

A variation to this driveline design would be to use a close tolerancecylindrical portion of the shaft at its distal end, instead of theaforementioned machined conical shape, which cylindrical shape wouldslide into a close tolerance bore inside the hub, with the axiallypositioned bolt securing the hub to the shaft. The movement of the hubrelative to the shaft would be limited to the clearance between theshaft and the bore. It would be anticipated, however, that the axiallypositioned bolt may be difficult to keep tight due to the motion betweenthe shaft and the hub bore. Accordingly, the driveline design describedabove and incorporating the machined conical surfaces to center theassembly on the shaft is preferred.

It will be understood that changes in the details, materials, steps andarrangements of parts which have been described and illustrated toexplain the nature of the invention will occur to and may be made bythose skilled in the art upon a reading of this disclosure within theprinciples and scope of the invention. The foregoing descriptionillustrates the preferred embodiment of the invention; however,concepts, as based upon the description, may be employed in otherembodiments without s departing from the scope of the invention.Accordingly, the following claims are intended to protect the inventionbroadly as well as in the specific form shown.

Having thus described the invention, what is claimed is:
 1. In aharvesting machine having a frame, harvesting apparatus supported fromsaid frame, and a draft tongue pivotally connected to said frame andextending forwardly thereof for connection to a prime mover havingwheels, the improvement comprising:a rearward end adapted for pivotalconnection to said implement frame; a rearward linear portion extendinglinearly from said rearward end; a forward curved portion integrallyformed with said linear portion and undertaking a horizontal deflection;and a distal hitch portion extending forwardly of said curved portionand being located to the right of a line extending forwardly of saidlinear portion due to said horizontal deflection of said curved portion,said curved portion being positioned immediately adjacent said hitchportion to be contiguous therewith such that said wheels of said primemover can be positioned adjacent thereto on turns involving a pivotalmovement between said prime mover and said hitch portion.
 2. Theharvesting machine of claim 1 wherein said distal hitch portion isformed with a generally vertical box section.
 3. The harvesting machineof claim 2 wherein said draft tongue is pivotally connected to saidframe and is pivotally movable to a shipping position that extendsgenerally laterally of said frame.